A synthetic quest for tris(imidazolyl) carboxylates and their metal complexes: active site models for quercetin 2,3-dioxygenases and other non-heme redox metalloenzymes
作者:Jerome Volkman、Kenneth M. Nicholas
DOI:10.1016/j.tet.2012.02.042
日期:2012.4
units and the carboxylate. A second route was developed, which provides more soluble ligands that are less prone to form oligomeric complexes. It utilizes addition of the Grignard reagent from 4-iodo-2-isopropylimidazole 12 to an imidazole diester 13, producing atropisomeric tris(imidazolyl)carbinol esters 15M. Treatment of 15M with [Cu(CH3CN)4]PF6 gives a trinuclear complex 16 having alkoxide bridges between
报道了合成三(咪唑基)羧酸酯配体和代表性金属络合物的途径,这为几类氧化还原金属酶提供了更准确的活性位点模型。在第一种方法中,将羟基新戊酸酯在四个区域选择性步骤中转化为咪唑二酯4。然后将其转化为三(咪唑基)羧酸配体9,其特征是将N保护的硫代咪唑的区域特异性双加成到咪唑二酯8上。配体9形成Co(III)络合物,(9)(9 -H)Co(10),通过X射线衍射表征,通过两个咪唑单元和羧酸酯进行配位。已开发出第二种途径,其提供了更多的易溶配体,这些配体不易形成寡聚复合物。它利用了将格氏试剂从4-碘-2-异丙基咪唑12加到咪唑二酯13中的方法,制得了阻转异构体的三(咪唑基)甲醇酯15M。用[Cu(CH 3 CN)4 ] PF 6处理15M,得到三核配合物16,其在相邻的Cu原子之间具有醇盐桥。第三种途径通过还原三(咪唑基)甲醇15M来避免桥接烷氧基生成三(咪唑基)甲烷酯17,将其水解为三(咪唑基)甲烷羧酸11a。该配体与[Cu(CH